Lubricating and protective coating



April 21, 1936. G|LL|$ 21,38,215

LUBRICATING AND PROTECTIVE .GQATING Filed Jan. 10, 1934 wan/04mm conmvs Patented Apr. 21, 1936 nunmcarmc AND rao'rsc'nvr:

COATING Randall Gillis, La Grange, Ill., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application January 10, 1934, Serial No. 706,066

2 Claims. (Cl. 201- 2) This invention relates to lubricating and protective coatings. I In the art of extruding metals, as for instance in the manufacture of lead covered cable, there 5 is frequently a tendency for the plastic or molten metal to adhere to the parts of the extruding apparatus with which it comes in contact and also to tools used in connection with such apparatus.

An object of the invention is to provide lubrieating and protective coatings to overcome this diillculty.

In accordance with one embodiment of the invention, a coating containing a solid lubricant is adhered to a surface by means of a temperature 5 resistant binder to prevent the plastic or molten metal from adhering to the surface.

Other objects and advantages will appear as the description proceeds.

A complete understanding of the invention may 20 by had by reference to the following description taken in conjunction with the accompanying drawing in which the single figure is a cross-sectional view of a lead press embodying the invention.

25 The invention has been illustrated'in 'connec- 35 extruding apparatus than lead-antimony alloys,

although when the invention is used'in connection with the latter alloys, a smoother and more uniform sheath is obtained. v

, In sheathing a telephone cable, the cable may 40 be fed through an elongated aperture '5 shown in the drawing. I The cable is fed from the'right to left, as viewed in the figure, and during the movement of the cable the lead in cylinder 0' is forced'by the ram 1 through a die 8 around the 45 cable. The internal'walls 8 of the die, as well as thev walls of the cylinder and surface of the ram, are provided with a protective lubricating coating. This coating may be applied by making an aqueous solution comprising 30 parts of sodium silicate, 8 parts oftartaric acid, 150 parts of powdered graphite and 1000 parts of water. These proportions are merely illustrative and are in no way critical and may be departed from in accordance with the results desired. The tar- '5' taric acid may be omitted, provided a sodium silicate is used which has a high silicate to sodium ratio. A thin coating of this solution is applied to the surfaces to be protected and is then evaporated to dryness, preferably by the applica- 10 tion of heat. The coating thus formed will with-- stand the high temperature and pressure encountered during the extruding operation and effectively prevents the sticking, soldering or adhering of the metal to the parts of the extrusion apparatus, especially when the metal to be extruded is allowed to cool below the point of solidification. I

When the plastic or molten lead adheres to the walls of the extrusion apparatus, it has a tendency to form what is known in the art as ruflled pipe and eccentric sheath. The application of the lubricating coating results in a uniform friction in the extruding .apparatus'and thus eliminates these difjflculties. Also when it becomes necessary to remove a die from the apparatus, it is .not necessary to melt out the lead due to the fact that the solidified lead does not adhere to the coated parts. t

,It will be understood that the nature and embodiment of the invention herein described and illustrated is merely a convenient and useful form of the invention and that many changes andmodiflcations may be made therein without departing from the spirit and scope of the inven- Q tion.. V

Whatis claimed is: 1. In an apparatus for extruding lead-calcium j alloys having surfaces adaptedto come in conof lead-calcium alloy, having surfaces adapted to come in contact with said alloys, a hardened dry coating of solid lubricant on 'said surfaces comprising a mixture of graphite and sodium silicate. p

- RANDALL GILLIS. 

